This invention relates to a method of producing intermediate structures from the rearrangement of alkylated phenols in the presence of an aluminum based catalyst. More particularly, this invention relates to the rearrangment of 2,4,6 trimethylphenol to provide 2,3,6-trimethylphenol in the presence of an aluminum based catalyst.
The ability to rearrange certain alkylated phenols, other than 2,4,6 trimethylphenol, in the presence of excess aluminum chloride has been disclosed by Baddeley, J. CHEM. SOC. Vol. 994, pp. 527-531 (1950). Baddeley does not achieve complete rearrangement of all the starting material in his process. The starting materials remain in equilibrium with the finished products, making the product yields low.
Fury and Pearson, J. Org. Chem. Vol. 30, pp. 2301-2304 (1965), disclose that complete rearrangment of the alkylated phenol starting material can be achieved by introducing anhydrous hydrogen chloride to the reaction medium with excess aluminum chloride. However, they do not obtain desirable reaction intermediates as finished products in the process they disclose. For example, Fury and Pearson disclose that the only product obtained upon rearrangement of 2,4,6 trimethylphenol is 2,3,5 trimethylphenol. They do not obtain 2,3,6 trimethylphenol from the rearrangment of 2,4,6 trimethylphenol and they do not indicate that such a product can be obtained.
This invention is based on the discovery that intermediate structures, such as 2,3,6 trimethylphenol, are produced in the rearrangement of certain methylated phenols, such as 2,4,6 trimethylphenol, and that these intermediate structures can be isolated from the reaction medium in high yields by controlling the rate of the rearrangement reaction. It has also been discovered that anhydrous hydrogen chloride need not be added to the reaction medium to obtain complete conversion of starting materials and high yields of intermediates where the reaction vessel is maintained under pressure and an acid generating catalyst is used.